Synthesis and characterization of three phthalocyanine-fullerene (Pc-C(60)) dyads, corresponding monoisomeric phthalocyanines (Pc), and building blocks, phthalonitriles, are described. Six novel bisaryl phthalonitriles were prepared by the Suzuki-Miyaura coupling reaction from trifluoromethanesulfonic acid 2,3-dicyanophenyl ester and various oxaborolanes. Two phthalonitriles were selected for the synthesis of A(3)B- and A(2)B(2)-type phthalocyanines. Phthalonitrile 4 has a bulky 3,5-di-tert-butylphenyl substituent at the alpha-phthalo position, which forces only one regioisomer to form and greatly increases the solubility of phthalocyanine. Phthalonitrile 8 has a 3-phenylpropanol side chain at the alpha-position making further modifications of the side group possible. Synthesized monoisomeric A(3)B- and A(2)B(2)-type phthalocyanines are modified by attachment of malonic residues. Finally, fullerene is covalently linked to phthalocyanine with one or two malonic bridges to produce Pc-C(60) dyads. Due to the monoisomeric structure and increased solubility of phthalocyanines, the quality of NMR spectra of the compounds is enhanced significantly, making detailed NMR analysis of the structures possible. The synthesized dyads have different orientations of phthalocyanine and fullerene, which strongly influence the electron transfer (ET) from phthalocyanine to fullerene moiety. Fluorescence quenchings of the dyads were measured in both polar and nonpolar solvents, and in all cases, the quenching was more efficient in the polar environment. As expected, most efficient fluorescence quenching was observed for dyad 20b, with two linkers and phthalocyanine and fullerene in face-to-face orientation.

The synthesis of a new azafullerene C(59)N-phthalocyanine (Pc) dyad is described. The key step for the synthesis of the C(59)N-Pc dyad was the formation of the C(59)N-based carboxylic acid, which was smoothly condensed with hydroxy-modified Pc. The structure of the C(59)N-Pc dyad was verified by (1)H and (13)C NMR spectroscopy, IR spectroscopy, UV/Vis spectroscopy and MS measurements. The photophysical and electrochemical properties of the C(59)N-Pc dyad were investigated in both polar and non-polar solvents by steady state and time-resolved photoluminescence and absorption spectroscopy, as well as by cyclic voltammetry. Different relaxation pathways for the photoexcited C(59)N-Pc dyad, as a result of changing the solvent polarity, were found, thus giving rise to energy-transfer phenomena in non-polar toluene and charge-transfer processes in polar benzonitrile. Finally, the detailed quenching mechanisms were evaluated and compared with that of a C(60)-Pc dyad, which revealed that the different excited-state energies and reduction potentials of the two fullerene spheres (i.e. C(59)N vs. C(60)) strongly diverged in the deactivation pathways of the excited states of the corresponding phthalocyanine dyads.

Photoinduced electron transfer reactions of phthalalocyanine-fullerene dyads, in which donor and acceptor moieties are covalently linked to each other, with one or two malonic linkers, were studied. In the dyads with two linkers, phthalocyanine and fullerene have mutual orientations, face-to-face or face-to-tail, which differ from each other and influence photoinduced electron transfer processes. Quantitative spectroscopic and time-resolved spectroscopic measurements were done in polar and non-polar solvents at room temperature and at several reduced temperatures. The emission spectra of the double-linked dyads were different from that of the reference phthalocyanine showing a shoulder at the red part of the spectrum, emission decays were two-exponential and emission lifetimes depend on monitoring wavelengths. These facts support, for the dyads with two linkers, the formation of an emissive intramolecular exciplex preceding the charge separated state. For these dyads the formation times of the charge separated state, approximately 0.4 ps and 0.8 ps for the face-to-face and face-to-tail isomers, respectively, were independent of temperature and the reaction is considered to be quantum tunneling in nature. The charge recombination times were temperature dependent, but decreased with the decrease of temperature from roughly 1.2 ns at room temperature to 0.7 ns at 190 K.

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Synthesis, characterization, molecular modeling, and photovoltage responses of four phthalocyanine−fullerene (Pc-C 60 ) dyads with two polar (−OH) side chains are described. The synthesized dyads have polar tails either on the Pc (electron donor D) side or on the fullerene (electron acceptor A) side of the dyad, providing a possibility to produce oriented donor−acceptor (D−A) monolayers with revised electron transfer direction when deposited on an aqueous subphase or on a solid surface. In the dyads, phthalocyanine and fullerene have different mutual orientations: in the trans-dyads they have face-to-face orientation, while in the cis-dyads the orientation is face-to-edge. Molecular modeling was used to examine and confirm the spatial arrangements of the synthesized dyads. The Pc-C 60 dyads were deposited successfully onto solid substrates as highly oriented monolayers using the Langmuir−Schafer method. Formation of a vertically oriented monolayer and the following electron transfer from the photoexcited phthalocyanine to fullerene was demonstrated for all dyad monolayers by the time-resolved Maxwell displacement charge method. The electron transfer direction was reversed for the dyads with reversed polarity, demonstrating the ability to control charge transfer direction in the film.

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Synthesis and characterization of two A 2 B 2-type monoisomeric phthalocyanines and phthalocyanine-fullerene (Pc- C 60) dyads, in which fullerene is regioselectively attached to phthalocyanine with two linkers, are described. 1 H NMR spectroscopy results clearly indicate an e addition pattern of the fullerene moiety in trans-dyad 9, and apparently a cis-3 addition pattern in cis-dyad 10. The possible spatial arrangements of 9 and 10 were further examined by molecular modeling. The dyads have polar (– OH ) side chains on the fullerene side of the dyad providing a possibility to produce oriented donor–acceptor (D–A) Langmuir monolayers on aqueous subphase, which can be shifted onto a solid surface. When deposited on a solid electrode material, parallel vertical alignment of the phthalocyanine and fullerene moieties in 100% dyad monolayer was obtained and vertical electron transfer from Pc to C 60 upon photoexcitation was demonstrated. Introduction of the dyads as an oriented interfacial monolayer between the photoactive layer and metal anode improved the power conversion efficiency in inverted organic solar cells.